[Solved: wet filament] Help me identify the problem: wet filament, bad z-height, or clogged nozzle?

This is a Prusa MINI+ that has worked flawlessly for 3 months. Suddenly the prints won't stick to the bed, the first layer is all messy and I cancel the print before anything worse happens.

• The printer has auto bed leveling so I would rule that out.
• The plate is cleaned with 70% IPA, so it's not dirty either.
• I have tried to adjust the "Live Z Adjust" while printing that first layer, but no setting works well.
• Each filament is printed at recommended temps (+/- 215C) and bed is at 60C.
• Out of my 5 spools, only 1 works well: RepRapper 3-color PLA. Even the Prusament PLA fails to stick well, and also eSun PLA+, and eSun matte PLA, and Tinmorry TPU.

https://i.imgur.com/MEpK37W.png

Update:

• Thank you all for your kind input.
• I washed the plate, and cleaned the nozzle (have no spare nozzle).
• I also did a fresh Z-test (with this object) using Prusament galaxy silver PLA.
• That was successful and showed that my height was already very close to perfect.
• Z-test result shows that -1.425 is best. I was off by only 0.025. Image
• Started printing an object with eSun matte black PLA but the result was same as in my original photo.
• Changed back to the Prusament galaxy silver PLA and the result is perfect. (image)

So it looks like my filament storage is not up to snuff! Good thing that I only have a few spools, so not much is lost.